| Description |
Molecular motors are nanoscale machines designed by nature to transport material over long distances inside the cell. Motors “walk” in a bipedal manner while carrying their cargo (for example, virus). Kinesin and Dynein are the two major motors for such transport. They generate force, and therefore transport cargo in opposite directions within the cell. These two motors are essential for the cell to function, and have been studied intensely for two decades using a variety of cross-disciplinary techniques. However, most biophysical measurements have been done under artificial test-tube conditions. We therefore do not understand how these motors work in a natural environment, where not one, but many opposing motors are known to transport a single cargo. The basic unsolved question is: How does the cell control activity of many opposing kinesin and dynein motors to transport cargo effectively and robustly?
We now report real-time optical trap-based measurement of the force generated by motors on single cellular cargoes. This allows us to precisely “count” the number of motors on a cargo, and to demonstrate for the first time that the two major motors (dynein and kinesin) work differently at the molecular level inside a cell. We show that two dissimilar teams of opposing motors engage in a physical tug-of-war. This tug-of-war is cleverly regulated by virtue of the dissimilarities between opposing motors and motor-teams to generate useful work.
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